Many sawing machines and vertical band saws, in particular, have an endless band-like blade that is mounted about two substantially flat, co-planar band wheels. Typically, the band wheels are situated such that there is an upper band wheel that is positioned above a horizontal work surface and a lower band wheel that is positioned below the horizontal work surface. The blade is then tensioned such that the blade moves with and along a portion of the outer perimeter of the band wheels, the blade having a toothed cutting edge that is used to cut material or stock that is located at the horizontal work surface. This is well known in the art of sawing machines.
In the art of such sawing machines and blades for such machines, it is also known that it is advantageous to rotate a portion of the blade at the horizontal work surface by 90° or so. In this way, there is no limit to the length of material or stock that can be cut by the blade. Without rotation of the blade in this fashion, the material or stock that can be cut is effectively limited in one direction by its length, which would be the distance between that portion of the cutting blade that is traveling in one direction and that portion of the cutting blade that is traveling in the opposite direction. Generally, this distance is the diameter of one or the other of the band wheels that are used in the saw. Rotation of the blade by 90° at the working surface eliminates this limitation. Rotation is typically effected by means of stationary guide means located above and below the horizontal work surface.
In sawing machines of this type, it is also necessary to replace the band-like blade, or band, with another from time to time. This is accomplished by releasing the tension between the upper and the lower band wheels, then removing that portion of the band from within the stationary guide means and finally removing the band from the machine. To install a new band, the operator must position a portion of the band above the upper band wheel and along its perimeter, position another portion of the band below the lower band wheel and about its perimeter, and then, by hand, twist a portion of the band at the horizontal working surface about 90° in order to place that portion of the band into the stationary guide mechanism. The guide mechanism typically consists of two guide assemblies, one above the working surface and one below, each having a slot within which the band is inserted. Typically, the blade guide assemblies will include carbide guides that are used to support the sides of the blade and a carbide-faced pressure block that is used to support the back edge of the blade. In this fashion, the guide assemblies apply a slight, forward pre-load to the band blade which effectively reduces noise and vibration during cutting. Once the band is in place, the band is properly tensioned and the sawing machine is ready for cutting.
In the view of this inventor, what is needed is an assembly that provides a blade guide that is rotatable such that the band can be placed about the band wheels and then, with the band in that position, the band can also be placed into the blade guide. The blade guide, with the band placed within it, can then be simply rotated by hand such that the desired cutting position of the blade is accomplished, as described above. What is also needed is a way to effectively secure the rotated blade guide in its rotated position for proper cutting. What is also needed is a way to provide two such rotating blade guide assemblies such that one can be located above the working surface and one below it. What is also needed is such a blade guide assembly that also tensions the band during normal use by using any variety of tensioning means of current manufacture that can be built into, or used with, the rotating blade guide assembly of the present invention.